"three types of muscle, skeletal or striated, cardiac, and smooth. Muscle action can be classified as being either voluntary or involuntary. Cardiac and smooth muscles contract without conscious thought and are termed involuntary, whereas the skeletal muscles contract upon command. Skeletal muscles in turn can be divided into fast and slow twitch fibers. Muscles are predominantly powered by the oxidation of fats and carbohydrates, but anaerobic chemical reactions are also used, particularly by fast twitch fibers. These chemical reactions produce adenosine triphosphate (ATP) molecules that are used to power the movement of the myosin heads. The term muscle is derived"
"Smooth muscle Smooth muscle is an involuntary non-striated muscle. It is divided into two subgroups; the single-unit (unitary) and multiunit smooth muscle. Within single-unit cells, the whole bundle or sheet contracts as a syncytium. Smooth muscle cells are found in the walls of hollow organs, including the stomach, intestines, urinary bladder and uterus, and in the walls of passageways, such as the arteries and veins of the circulatory system, and the tracts of the respiratory, urinary, and reproductive systems. These cells are also present in the eyes and are able to change the size of the iris and alter the"
"smooth muscle of blood vessels and various other tissues, and can mostly be found in two forms: tissue-bound and soluble isoforms. The tissue-bound SSAO is primarily located in the leukocytes, adipocytes, and the endothelium of highly vascularized tissues, including the kidney, liver, and gonads. Thus, this form participates in cellular differentiation, deposition of the ECM (extracellular matrix) in smooth muscle cells, lipid trafficking in adipocytes and control of muscular tone, by mechanisms that are not completely understood. The soluble form, which is commonly known as VAP-1, is a proinflammatory protein derived from shedding of the transmembrane protein. It is highly"
"in such organs as sea anemone tentacles and the body wall of sea cucumbers. Skeletal muscle contracts rapidly but has a limited range of extension. It is found in the movement of appendages and jaws. Obliquely striated muscle is intermediate between the other two. The filaments are staggered and this is the type of muscle found in earthworms that can extend slowly or make rapid contractions. In higher animals striated muscles occur in bundles attached to bone to provide movement and are often arranged in antagonistic sets. Smooth muscle is found in the walls of the uterus, bladder, intestines, stomach,"
"of certain minerals. Calcium and phosphorus are among the main minerals being stored. The importance of this storage ""device"" helps to regulate mineral balance in the bloodstream. When the fluctuation of minerals is high, these minerals are stored in bone; when it is low it will be withdrawn from the bone. There are three types of muscles—cardiac, skeletal, and smooth. Smooth muscles are used to control the flow of substances within the lumens of hollow organs, and are not consciously controlled. Skeletal and cardiac muscles have striations that are visible under a microscope due to the components within their cells."
"neurotransmitters). Smooth muscle is found within the walls of various organs and tubes in the body such as the esophagus, stomach, intestines, bronchi, urethra, bladder, and blood vessels. Although smooth muscles do not form regular arrays of thick and thin filaments like the sarcomeres of striated muscles, contraction is still due to the same sliding filament mechanism controlled by myosin crossbridges interacting with actin filaments. The thin filament of smooth muscle is made of actin, tropomyosin, caldesmon, and calmodulin. Within this type of muscle, caldesmon and calmodulin control the tropomyosin-mediated transition between on and off activity states. Caldesmon binds to"
"detailed below. Smooth muscle may contract spontaneously (via ionic channel dynamics) or as in the gut special pacemakers cells interstitial cells of Cajal produce rhythmic contractions. Also, contraction, as well as relaxation, can be induced by a number of physiochemical agents (e.g., hormones, drugs, neurotransmitters – particularly from the autonomic nervous system). Smooth muscle in various regions of the vascular tree, the airway and lungs, kidneys and vagina is different in their expression of ionic channels, hormone receptors, cell-signaling pathways, and other proteins that determine function. For instance, blood vessels in skin, gastrointestinal system, kidney and brain respond to norepinephrine"
"to keep warm. Skeletal muscles, like other striated muscles, are composed of myocytes, or muscle fibers, which are in turn composed of myofibrils, which are composed of sarcomeres, the basic building block of striated muscle tissue. Upon stimulation by an action potential, skeletal muscles perform a coordinated contraction by shortening each sarcomere. The best proposed model for understanding contraction is the sliding filament model of muscle contraction. Within the sarcomere, actin and myosin fibers overlap in a contractile motion towards each other. Myosin filaments have club-shaped heads that project toward the actin filaments. Larger structures along the myosin filament called"
"Skeleton The skeleton is the body part that forms the supporting structure of an organism. There are several different skeletal types: the exoskeleton, which is the stable outer shell of an organism, the endoskeleton, which forms the support structure inside the body, the hydroskeleton, and the cytoskeleton. The term comes . There are two major types of skeletons: solid and fluid. Solid skeletons can be internal, called an endoskeleton, or external, called an exoskeleton, and may be further classified as pliant (elastic/movable) or rigid (hard/non-movable). Fluid skeletons are always internal. Exoskeletons are external, and are found in many invertebrates; they"
"the urinary bladder, uterus (termed uterine smooth muscle), male and female reproductive tracts, gastrointestinal tract, respiratory tract, arrector pili of skin, the ciliary muscle, and iris of the eye. The structure and function is basically the same in smooth muscle cells in different organs, but the inducing stimuli differ substantially, in order to perform individual effects in the body at individual times. In addition, the glomeruli of the kidneys contain smooth muscle-like cells called mesangial cells. Cardiac muscle is involuntary, striated muscle that is found in the walls and histological foundation of the heart, specifically the myocardium. Cardiac muscle is"
"1:3 range. A typical value for healthy young adults is 1:2.2.;; Smooth muscle does not contain the protein troponin; instead calmodulin (which takes on the regulatory role in smooth muscle), caldesmon and calponin are significant proteins expressed within smooth muscle. Also, all three of these proteins may have a role in inhibiting the ATPase activity of the myosin complex that otherwise provides energy to fuel muscle contraction. The myosin and actin are the contractile parts of continuous chains of tensile structures that stretch both across and between smooth muscle cells. The actin filaments of contractile units are attached to ""dense"
"Muscular system of the horse There are 3 types of muscle, all found within the equine: Skeletal muscle is made up of several muscle bundles, which in turn are made up of muscle fibers. Muscle fibers have bundles of myofibrils, which are all parallel to one another, and are able to contract due to actin and myosin. Muscle is covered by a fibrous tissue called fascia, to which other muscles can attach, and muscles attach to bone via tendons. Tendons attach muscles and bone, and are classified as flexors (flex a joint) or extensors (extend a joint). However, some tendons"
"muscle tissue. Smooth muscle may contract phasically with rapid contraction and relaxation, or tonically with slow and sustained contraction. The reproductive, digestive, respiratory, and urinary tracts, skin, eye, and vasculature all contain this tonic muscle type. This type of smooth muscle can maintain force for prolonged time with only little energy utilization. There are differences in the myosin heavy and light chains that also correlate with these differences in contractile patterns and kinetics of contraction between tonic and phasic smooth muscle. Crossbridge cycling cannot occur until the myosin heads have been activated to allow crossbridges to form. When the light"
"between species and between muscles in a single individual. The reasons for the lack of substantial sarcomere variability in vertebrates is not fully known. Sarcomere A sarcomere (Greek ""sarx"" ""flesh"", ""meros"" ""part"") is the basic unit of striated muscle tissue. It is the repeating unit between two Z lines. Skeletal muscles are composed of tubular muscle cells (myocytes called muscle fibers or myofibers) which are formed in a process known as myogenesis. Muscle fibers contain numerous tubular myofibrils. Myofibrils are composed of repeating sections of sarcomeres, which appear under the microscope as alternating dark and light bands. Sarcomeres are composed"
"J. DMV, and Susan E. Hakola DMV. Illustrated Atlas of Clinical Equine Anatomy and Common Disorders of the Horse Vol. II. Equistar Publication, Limited. Marysville, OH. Copyright 2000. Muscular system of the horse There are 3 types of muscle, all found within the equine: Skeletal muscle is made up of several muscle bundles, which in turn are made up of muscle fibers. Muscle fibers have bundles of myofibrils, which are all parallel to one another, and are able to contract due to actin and myosin. Muscle is covered by a fibrous tissue called fascia, to which other muscles can attach,"
"upper arms, thighs, and hips. Skeletal muscle is made up of two kinds of fiber, type 1 and type 2. In congenital fiber type disproportion, type 1 fibers are not only smaller but often more abundant than type 2 fibers. This leads to affected individuals being able to maintain an active lifestyle, though they usually have lower levels of stamina. Severity with this disease varies greatly, but people typically present symptoms by the age of one. Individuals do not usually worsen with time, and cases have even been reported of improvements. Multicore myopathy, also referred to as minicore myopathy, is"
"muscle tissue approximately 15% denser than fat tissue. Skeletal muscles are sheathed by a tough layer of connective tissue called the epimysium. The epimysium anchors muscle tissue to tendons at each end, where the epimysium becomes thicker and collagenous. It also protects muscles from friction against other muscles and bones. Within the epimysium are multiple bundles called fascicles, each of which contains 10 to 100 or more muscle fibers collectively sheathed by a perimysium. Besides surrounding each fascicle, the perimysium is a pathway for nerves and the flow of blood within the muscle. The threadlike muscle fibers are the individual"
"Actinin alpha 3 Alpha-actinin-3, also known as alpha-actinin skeletal muscle isoform 3 or F-actin cross-linking protein, is a protein that in humans is encoded by the ""ACTN3"" gene. Alpha-actinin is an actin-binding protein with multiple roles in different cell types. This gene expression is limited to skeletal muscle. It is localized to the Z-disc and analogous dense bodies, where it helps to anchor the myofibrillar actin filaments. Skeletal muscle is composed of long cylindrical cells called muscle fibers. There are two types of muscle fibers, slow twitch or muscle contraction (type I) and fast twitch (type II). Slow twitch fibers"
"heart, lungs, upper gastrointestinal tract, and sweat glands. Acetylcholine is the substance the nervous system uses to activate skeletal muscles, a kind of striated muscle. These are the muscles used for all types of voluntary movement, in contrast to smooth muscle tissue, which is involved in a range of involuntary activities such as movement of food through the gastrointestinal tract and constriction of blood vessels. Skeletal muscles are directly controlled by motor neurons located in the spinal cord or, in a few cases, the brainstem. These motor neurons send their axons through motor nerves, from which they emerge to connect"
"to demonstrate greater elasticity and function within a larger length-tension curve than striated muscle. This ability to stretch and still maintain contractility is important in organs like the intestines and urinary bladder. In the relaxed state, each cell is spindle-shaped, 20–500 micrometers in length. A substantial portion of the volume of the cytoplasm of smooth muscle cells are taken up by the molecules myosin and actin, which together have the capability to contract, and, through a chain of tensile structures, make the entire smooth muscle tissue contract with them. Myosin is primarily class II in smooth muscle. Different combinations of"
"shape of the lens. In the skin, smooth muscle cells cause hair to stand erect in response to cold temperature or fear. Most smooth muscle is of the single-unit variety, that is, either the whole muscle contracts or the whole muscle relaxes, but there is multiunit smooth muscle in the trachea, the large elastic arteries, and the iris of the eye. Single unit smooth muscle, however, is most common and lines blood vessels (except large elastic arteries), the urinary tract, and the digestive tract. However, the terms single- and multi-unit smooth muscle represents an oversimplification. This is due to the"
"is striated initially, but then becomes smooth muscle in the caudal third or so. In canines and ruminants, however, it is entirely striated to allow regurgitation to feed young (canines) or regurgitation to chew cud (ruminants). It is entirely smooth muscle in amphibians, reptiles and birds. Contrary to popular belief, an adult human body would not be able to pass through the esophagus of a whale, which generally measures less than in diameter, although in larger baleen whales it may be up to when fully distended. A structure with the same name is often found in invertebrates, including molluscs and"
"Sarcomere A sarcomere (Greek ""sarx"" ""flesh"", ""meros"" ""part"") is the basic unit of striated muscle tissue. It is the repeating unit between two Z lines. Skeletal muscles are composed of tubular muscle cells (myocytes called muscle fibers or myofibers) which are formed in a process known as myogenesis. Muscle fibers contain numerous tubular myofibrils. Myofibrils are composed of repeating sections of sarcomeres, which appear under the microscope as alternating dark and light bands. Sarcomeres are composed of long, fibrous proteins as filaments that slide past each other when a muscle contracts or relaxes. Two of the important proteins are myosin,"
"muscular ""slip"" is a narrow length of muscle that acts to augment a larger muscle or muscles. The muscular system is one component of the musculoskeletal system, which includes not only the muscles but also the bones, joints, tendons, and other structures that permit movement. All muscles are derived from paraxial mesoderm. The paraxial mesoderm is divided along the embryo's length into somites, corresponding to the segmentation of the body (most obviously seen in the vertebral column. Each somite has 3 divisions, sclerotome (which forms vertebrae), dermatome (which forms skin), and myotome (which forms muscle). The myotome is divided into"
"to the origin and insertion tendons at each end. Because the contracting fibers are pulling at an angle to the overall action of the muscle, the change in length is smaller, but this same orientation allows for more fibers (thus more force) in a muscle of a given size. Pennate muscles are usually found where their length change is less important than maximum force, such as the rectus femoris. Skeletal muscle is arranged in discrete muscles, an example of which is the ""biceps brachii"" (biceps). The tough, fibrous epimysium of skeletal muscle is both connected to and continuous with the"
"important attribute of smooth muscle. Smooth muscle cells may secrete a complex extracellular matrix containing collagen (predominantly types I and III), elastin, glycoproteins, and proteoglycans. Smooth muscle also has specific elastin and collagen receptors to interact with these proteins of the extracellular matrix. These fibers with their extracellular matrices contribute to the viscoelasticity of these tissues. For example, the great arteries are viscolelastic vessels that act like a Windkessel, propagating ventricular contraction and smoothing out the pulsatile flow, and the smooth muscle within the tunica media contributes to this property. The sarcolemma also contains caveolae, which are microdomains of lipid"
"crest. The iliocostalis has three different insertions according to the parts: The longissimus muscle is the intermediate and the largest of the three columns. It has three parts with different origin and insertion: The spinalis muscle is the smallest and most medial column. It has three parts: From lateral to medial, the erector spinae muscles can be remembered using the mnemonic, I Love Spine. I lliocostalis, Love Longissimus and Spine Spinalis. Examples of exercises by which the erector spinae can be strengthened for therapeutic or athletic purposes include, but are not limited to: Erector spinae muscles The erector spinae ("
"Stapedius muscle The stapedius is the smallest skeletal muscle in the human body. At just over one millimeter in length, its purpose is to stabilize the smallest bone in the body, the stapes. The stapedius emerges from a pinpoint foramen in the apex of the pyramidal eminence (a hollow, cone-shaped prominence in the posterior wall of the tympanic cavity), and inserts into the neck of the stapes. The stapedius is supplied by the nerve to stapedius, a branch of the facial nerve. The stapedius dampens the vibrations of the stapes by pulling on the neck of that bone. It prevents"
"body that produce sustained contractions. Cardiac muscle make up the heart, which pumps blood. Skeletal and cardiac muscles are called striated muscle because of their striped appearance under a microscope, which is due to the highly organized alternating pattern of A bands and I bands. Excluding reflexes, all skeletal muscles contractions occur as a result of conscious effort originating in the brain. The brain sends electrochemical signals through the nervous system to the motor neuron that innervates several muscle fibers. In the case of some reflexes, the signal to contract can originate in the spinal cord through a feedback loop"
"Gluteal muscles The gluteal muscles are a group of three muscles which make up the buttocks: the gluteus maximus, gluteus medius and gluteus minimus. The three muscles originate from the ilium and sacrum and insert on the femur. The functions of the muscles include extension, abduction, external rotation and internal rotation of the hip joint. The gluteus maximus is the largest and most superficial of the three gluteal muscles. It makes up a large portion of the shape and appearance of the hips. It is a narrow and thick fleshy mass of a quadrilateral shape, and forms the prominence of"
"the somites. To form skeletal muscle in central body segments, PAX3-expressing cells detach from the dermomyotome and then Pax3 expression is turned off as Myf5 and MyoD1 expression is activated. To form other skeletal muscles, Pax3-expressing cells detach from the dermomyotome and migrate to more distant sites, such as the limbs and diaphragm. A subset of these Pax3-expressing dermomyotome-derived cells also serves as an ongoing progenitor pool for skeletal muscle growth during fetal development. During later developmental stages, myogenic precursors expressing Pax3 and/or Pax7 form satellite cells within the skeletal muscle, which contribute to postnatal muscle growth and muscle regeneration."
"Gluteus maximus The gluteus maximus (also known collectively with the gluteus medius and minimus, as the gluteal muscles, and sometimes referred to informally as the ""glutes"") is the main extensor muscle of the hip. It is the largest and most superficial of the three gluteal muscles and makes up a large portion of the shape and appearance of each side of the hips. Its thick fleshy mass, in a quadrilateral shape, forms the prominence of the buttocks. Its large size is one of the most characteristic features of the muscular system in humans, connected as it is with the power"
"action of the muscle, the change in length is smaller, but this same orientation allows for more fibers (thus more force) in a muscle of a given size. Pennate muscles are usually found where their length change is less important than maximum force, such as the rectus femoris. Skeletal muscle is arranged in discrete muscles, an example of which is the ""biceps brachii"". The tough, fibrous epimysium of skeletal muscle is both connected to and continuous with the tendons. In turn, the tendons connect to the periosteum layer surrounding the bones, permitting the transfer of force from the muscles to"